During the first year of this award, twenty-one measles virus-specific T cell clones have been derived from a twin with multiple sclerosis. Preliminary genetic restriction studies have been performed with 18 of these clones in terms of accessory cell-T cell interactions. These studies will be completed. Of particular interest are six clones to which antigen is presented by autologous and twin-derived accessory cells, but by few, if any, of the allogeneic accessory cells which have been examined to date and which are matched for HLA-D, -DR, and -SB region gene products. Similar studies will be performed with a panel of antigen-presenting cells obtained from MS patients. If any of these clones appear to recognize measles antigen in association with a gene product closely linked to the presence of disease, these clones will be studied with respect to the nature of the cell surface structure(s) involved with antigen recognition, and compared with clones which recognize antigen in clear association with HLA-DR or -SB region gene products. The fine antigenic specificities of the clones will be tested against individual measles virus polypeptides separated on and eluted from polyacrylamide gels. The peptides studied will include the hemagglutinin and the nucleocapsid, fusion, matrix, and P proteins. The clones will also be screened for cytotoxic T lymphocyte (CTL) and natural killer cell activity. Clones demonstrating measles specific CTL activity will be evaluated in additional genetic restriction studies.